1. Field of the Invention
This invention relates generally to electronic speech recognition systems, and relates more particularly to a system and method for speech verification using an efficient confidence measure.
2. Description of the Background Art
Implementing an effective and efficient method for system users to interface with electronic devices is a significant consideration of system designers and manufacturers. Voice-controlled operation of electronic devices is a desirable interface for many system users. For example, voice-controlled operation allows a user to perform other tasks simultaneously. For instance, a person may operate a vehicle and operate an electronic organizer by voice control at the same time. Hands-free operation of electronic systems may also be desirable for users who have physical limitations or other special requirements.
Hands-free operation of electronic devices may be implemented by various speech-activated electronic systems. Speech-activated electronic systems thus advantageously allow users to interface with electronic devices in situations where it would be inconvenient or potentially hazardous to utilize a traditional input device. Electronic entertainment systems may also utilize speech recognition techniques to allow users to interact with a system by speaking to it.
Speech-activated electronic systems may be used in a variety of noisy environments such as industrial facilities, manufacturing facilities, commercial vehicles, passenger vehicles, homes, and office environments. A significant amount of noise in an environment may interfere with and degrade the performance and effectiveness of speech-activated systems. System designers and manufacturers typically seek to develop speech-activated systems that provide reliable performance in noisy environments. In a noisy environment, sound energy detected by a speech-activated system may contain speech and a significant amount of noise. In such an environment, the speech may be masked by the noise and be undetected. This result is unacceptable for reliable performance of the speech-activated system.
Alternatively, sound energy detected by the speech-activated system may contain only noise. The noise may be of such a character that the speech-activated system identifies the noise as speech. This result reduces the effectiveness of the speech-activated system, and is also unacceptable for reliable performance. Verifying that a detected signal is actually speech increases the effectiveness and reliability of speech-activated systems.
A speech-activated system may have a limited vocabulary of words that the system is programmed to recognize. The system should respond to words or phrases that are in its vocabulary, and should not respond to words or phrases that are not in its vocabulary. Verifying that a recognized word is in the system's vocabulary increases the accuracy and reliability of speech-activated systems.
Therefore, for all the foregoing reasons, implementing an effective and efficient method for a system user to interface with electronic devices remains a significant consideration of system designers and manufacturers.